We have developed methods for the immunological purification of polysomes and mRNA specific for a given globin chain. These globin chain-specific mRNAs and their derivative cDNA and sDNA will be used to determine: 1) the precise number of genes coding for specific globin chains in the rabbit and man; 2) the distance between linked genes; and 3) the isolation and characterization of DNA sequences between linked genes. Th human Y chromosome contains two distinctive Hae III restriction enzyme fragments. We have analyzed the chromosomal location and internal sequence arrangement of the larger (3.4 kb) fragment. A similar analysis of the smaller (1.9 kb) fragment will be undertaken. These studies will involve (1) reassociation analysis with whole genome male and female DNA of man and a number of primates; (2) homology relationships with the 3.4 kb fragment and it-Y DNA; (3) sequence analysis of the 1.9 kb fragment; and (4) analysis of a number of morphologically and functionally variant Y chromosomes for the presence and arrangement of the 1.9 kb fragment.